What does graphene do in transistors instead of Silicon?

Graphene is known by the media as a miracle material because of its excellent electrical, optical and mechanical properties. In recent years, it has attracted many scientists and a large amount of research funds. The discovery of graphene was awarded the 2010 Nobel Prize in physics. Recently, however, IBM researchers claimed that the application prospects of graphene may be exaggerated because the properties of graphene itself cause some obstacles to graphene research.

"Not likely to replace Silicon."

Graphene is a two-dimensional grid structure composed of single-layer carbon atoms and is the basic unit that constitutes other carbon allotropes. Theoretical research on graphene has been for decades, but no one previously believed that graphene could be stable. In 2004, Gem, Dr. Novoselov, a physics professor at the University of Manchester in the United Kingdom, used regular tape bought from supermarkets to repeatedly strip highly directional pyrolytic graphite to obtain stable graphene. The discovery immediately attracted the attention of physicists, chemists, and materials scientists, and set off another wave of research on carbon materials. In 2010, Geim and Novoselov were awarded the annual Nobel Prize in physics for the discovery of graphene, and the application prospects of graphene are more promising.

As a transistor manufacturing material is the most critical content in the application of graphene, the material commonly used to prepare transistors is Silicon, but when the crystal tube gate prepared with Silicon is less than 5 nm, the transistor will fail, and graphene does not exist. Such a problem. However, recent IBM scientist Yu-MingLin said graphene is unlikely to replace Silicon.

In early 2010, IBM published a paper in Science magazine announcing that they had used graphene transistors to make circuits up to 100 GHz. But Yu-Minglin began telling the media in 2011 that there is a clear difference between the transistors they make with graphene and the transistors used in the CPU. The graphene transistor does not have an energy gap and therefore can not be "completely turned off", which means that more energy will leak and cause overheating. So the prospect of completely replacing Silicon with graphene is less promising, but Lin says graphene and Silicon can complement each other to expand the capabilities of computer chips in the form of hybrid circuits.

In this regard, Professor Kang Feiyu of the Department of Materials Science and Engineering of Tsinghua University believes that the current energy gap problem of graphene is controversial, and research on changing the energy gap by using doping technology is still underway.

The future is infinite, and transistor research is concerned.

Prior to the discovery of graphene, the physics community believed that thermodynamic fluctuations did not allow two-dimensional crystals to exist at finite temperatures. However, the discovery of graphene had a huge impact on physical cognition at the time and was immediately depicted as a promising application. Graphene has very excellent performance. It has an oversized specific surface area and good mechanical properties. In addition, graphene has a thermal conductivity of 10 times that of copper; Its light permeability is good, and the absorption rate of light is only 2.3 %; It has many peculiar properties in terms of electrical and magnetic properties, such as room temperature quantum Hall effect, bipolar electric field effect, ferromagnetism, superconductivity, and high electron mobility. These excellent qualities make graphene have good application prospects in transistors, solar cells, supercapacitors, field emission and catalyst carriers.

In addition to the above-mentioned alternative Silicon as a transistor material, graphene can also be used in solar cells. The important part of the solar cell is the window electrode. At present, the commonly used window electrode material is the indium tin oxide semiconductor transparent film (ITO), but the content of indium is limited on the earth, and the ITO has poor light permeability in the near-infrared region. And unstable under acidic conditions, It is not conducive to the preparation of flexible devices, and graphene is considered to be a suitable material for replacing ITO.

In addition, because graphene adsorbs gas molecules, its conductivity changes, so graphene can be used as a gas sensor, and the advantage is obvious. In addition, with the increase in the demand for portable electronic equipment, the performance of supercapacitors is facing challenges. Finding suitable electrode materials is an important way to improve the performance of supercapacitors. The excellent performance of graphene is considered to be an ideal material for supercapacitor electrodes.

Graphene has more than that. Dr Geim, who once compared graphene to plastic, believes that graphene can develop a wide variety of materials, just like plastic, that can be applied to all corners of life in the future. Researchers have also found that graphene can be used as bandages, food packaging and even antibacterial T-shirts; It can also be used to develop and manufacture paper-thin ultra-light aircraft materials and ultra-tough body armor; Scientists even pinned their dreams of building a 23000 mile long space elevator on graphene.

"Although graphene has good applications in many fields, making transistor devices as a substitute material for Silicon is an important part of scientists 'expectations and one of the areas that have received the most attention. "Deputy researcher Guohaiming of the Institute of Physics of the Chinese Academy of Sciences told the" Science and Technology Guide. "

The field of transistors is facing difficulties.

Although the media and some scientists have been excited about the discovery of graphene in recent years, many researchers are still cautious and believe that the future of graphene application may be slightly optimistic because graphene is indeed in the transistor field. Difficulties.

Kangfeiyu, a researcher, told the Science Guide that he believes graphene is still far from being used. Because graphene has only one carbon atom layer, it is very difficult to prepare a graphene membrane that is not defective for industrial applications. In addition, graphene needs to be combined with other materials. A lot of research and exploration.

Dr. Cui Tongxiang, Department of Materials Science and Engineering, Tsinghua University, told reporters that graphene is a single crystal material, but it is often superimposed into a polycrystalline material in the application, and the polycrystalline material is not conducive to electron transport because of the existence of grain boundaries. This has become a deficiency of graphene.

Guohaiming, associate researcher, told technology guide that graphene applications in transistors or nanoscale devices now face many difficulties and challenges, not surprisingly, in addition to energy gap problems, there are also process problems. For example, large areas of high-quality graphene preparation, border tailoring control, device assembly, etc., but like any new thing, graphene should be given time and confidence, the problem will always be solved over time, at least to bring us Some new methods and ideas. Guohaiming also said that even without considering future applications, graphene, as an ideal two-dimensional single-layer atomic crystal material, contains a series of surprising specific electronic and physical properties that are worth investing in.

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